Re: asynch I/O

I just hit a description of async IO in Oracle docs, it is very simply
described there:

<quote>
With synchronous I/O, when an I/O request is submitted to the operating
system, the writing process blocks until the write is confirmed as complete.
It can then continue processing.
Asynchronous I/O allows a process to submit an I/O request but to then
continue processing. It may then check on the result of the I/O at a later
time. It is also possible to submit several I/O requests and then collect
the status of those requests at a later time, thus allowing the operating
system to parallelize any of those I/O operations, where possible. Parallel
processing can reduce the overall time to complete an operation.

Consider an extreme example: Imagine you want to write out four data blocks
to four different files. With synchronous I/O you must submit block 1, wait,
submit block 2, wait, submit block 3, wait, submit block 4, and wait. With
asynchronous I/O, you can submit blocks 1, 2, 3, and 4 and then wait for all
four blocks to complete. Because you gave the operating system all four I/O
requests at once, it can act on all the requests in parallel. The total
response time is only the duration of the longest I/O of the four, rather
than the sum of all four I/O durations.

> Ryan,>> You can have separate mount points from your server's perspective, but
once you get into the NetApp it's just a pool of disk drives that are
allocated as necessary by their WAFL (Write Anywhere File Layout) system.
Therefore in reality you get zero benefit.
>> Dick Goulet> Senior Oracle DBA> Oracle Certified 8i DBA>> -----Original Message-----> Sent: Thursday, September 18, 2003 10:10 PM> To: Multiple recipients of list ORACLE-L>>> Could you clarify something for me? Are you saying that if I have a
variety
> of 'mounts' on our netapp>> say>> /mnt1> /mnt2>> I would not benefit by putting my datafiles on seperate ones? I thought
that
> is where my I/O waits are coming from. Since we have all of our datafiles
in
> the same directory?>> -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net> -- > Author: Ryan> INET: rgaffuri_at_cox.net>> Fat City Network Services -- 858-538-5051 http://www.fatcity.com> San Diego, California -- Mailing list and web hosting services> ---------------------------------------------------------------------> To REMOVE yourself from this mailing list, send an E-Mail message> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in> the message BODY, include a line containing: UNSUB ORACLE-L> (or the name of mailing list you want to be removed from). You may> also send the HELP command for other information (like subscribing).> -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net> -- > Author: Goulet, Dick> INET: DGoulet_at_vicr.com>> Fat City Network Services -- 858-538-5051 http://www.fatcity.com> San Diego, California -- Mailing list and web hosting services> ---------------------------------------------------------------------> To REMOVE yourself from this mailing list, send an E-Mail message> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in> the message BODY, include a line containing: UNSUB ORACLE-L> (or the name of mailing list you want to be removed from). You may> also send the HELP command for other information (like subscribing).>

--
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--
Author: Tanel Poder
INET: tanel.poder.003_at_mail.ee
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